Malware torrent delivered over Google, Yahoo! ad services

Some of the web's bigger websites were flooded with a torrent of malicious banner ads after cyber crooks managed to sneak them onto syndication services operated by Google, Yahoo, and a third company, according to a security firm.

The ads - which attacked previously-patched vulnerabilities in Adobe's PDF Reader and Microsoft's DirectShow - starting appearing on sites such as the DrudgeReport, horoscope.com and lyrics.com last Friday, ScanSafe researcher Mary Landesman told The Register. They were delivered over networks belonging to Google's DoubleClick; Right Media'sYield Manager (owned by Yahoo); and Fastclick, owned by an outfit called ValueClick.

End users visiting sites that used the ad syndication services often saw nothing more than a brief flash as the malware-laced ads caused their browsers to open - and then close - a booby-trapped PDF file. But behind the scenes, the payload installed Win32/Alureon, a trojan that drops a backdoor on infected machines.

The malicious ads, which also appeared on slacker.com, ended on Monday, when the website used by the malware purveyors abruptly vanished. During their three-day stint, the attacks accounted for 11 percent of pages blocked by ScanSafe, a service used by businesses to prevent employees from visiting malicious sites.

The report, issued Wednesday, came the same day a Google executive called on internet service providers, website operators, and others to do more to combat malicious ads. Over the past few years, so-called malvertisements - which employ social-engineering and exploit code targeting vulnerabilities in operating systems and applications - have become an increasingly common way of spreading malware to the masses.

Of course, none of this would be possible without the help of the ad syndication services, which provide the software and services webmasters use to display ads to hundreds of millions of end users. DoubleClick, Right Media, and other networks have repeatedly been found to distribute malware-laced banner ads on of the net's most popular sites.

A spokesman for Google said the content of ads are up to websites that use the service.

"With DoubleClick ad management, publishers are in control of what content they are serving and are therefore ultimately responsible for determining what advertising appears on their site," a Google spokesman, who asked that his name not be included in this article, wrote in an email. "The publisher sells the space to the advertiser and must approve the content that goes on the site before it is introduced into DoubleClick's servers."

He went on to say that DoubleClick does employ a security monitoring system that screens all ads, and in cases where it identifies problem banners, they are pulled immediately.

"We believe that all members of the online advertising ecosystem should take an active role in malvertising prevention," the spokesman added.

No doubt, The DrudgeReport, horoscope.com, lyrics.com, and slacker.com should be called to account for the attacks on their users. And so far, none of those websites has responded to requests to comment. And neither did representatives for Yahoo or ValueClick, either. That doesn't inspire confidence that any of those companies are doing nearly enough to protect their visitors from a growing threat.

Which brings us back to Google, owner of far and away the biggest ad syndication service, and a company that's gone out of its way to lecture the rest of the industry to take a strong stand against malvertising. Slogans and speeches are all well and good, but as the continued attacks shows, revolution begins in the mirror. ®